One or more embodiments of the subject matter described herein generally relate to the deposition of dielectric and/or polymer materials onto a conductive substrate to form composite assemblies for electrical connectors.
Growing demands for miniaturization, improved performance, and reduced cost and weight of electronic components has driven intense research for novel materials and manufacturing processes to meet these demands. In order to improve signal quality in high speed electrical connectors, capacitive elements may be included along or near the signal path in the connector and/or at a mating interface between the connector and another mating connector. For example, some known connectors are mounted onto circuit boards with capacitors mounted onto the printed circuit board adjacent to the connectors and along the signal path extending from the connector and through the circuit board. Adding discrete capacitors to circuit boards, however, consumes additional real estate of the limited available surface area on the circuit board.
Other known connectors include a separate, discrete capacitor that is coupled to the signal paths in the connectors using known manufacturing methods, such as solder. Joining a separate capacitor to the signal path, however, may lead to problems in matching the electrical impedance of the signal path with the impedance through the capacitor and circuit board. Additionally, solder may introduce risks of reliability concerns as the joint between the solder and the signal path of the connectors can be brittle and easy to break. Additional methods to attach a discrete capacitor to the connector, such as epoxy application, present problems with adhesion, leading to fracture and cracking of the joint.
Some known capacitive elements are created by covering a conductive tape with a thin film of dielectric material. Adhesion of the dielectric material to the conductive tape is generally poor, thereby resulting in delamination of the dielectric material from the conductive tape. Additionally, the dispersion of the dielectric material on the tape may be uneven, resulting in an inhomogeneous dispersion of the dielectric material on the tape. This may result in non-uniform signal integrity across the connector.
Other capacitive elements may be created using processing techniques that involve relatively expensive processes and relatively high processing temperatures in order to get dielectric materials with relatively high dielectric constants to adhere to conductive bodies. For example the application of traditional high Dk materials and/or precursors—such as barium titanate, strontium titanate, tantalum oxides, and lead-based metal oxides—may require annealing temperatures well above the anneal temperature of the base metal of the connector. These processes may also result in relatively poor adhesion between the dielectric materials and the conductive bodies.